The present inventions concerns a device for guiding a rod-shaped member formed of a material adapted to be softened upon the application of heat when inserted into the guide channel of a heating apparatus which includes an elastic flexible cartridge having one end attached to the guide channel of the heating apparatus.
A capability of the type described above is required, for example, in devices commonly referred to as gluing guns which heat and soften an inserted rod formed of a gluing material. The apparatus typically utilizes electric heating apparatus which heats the rod to convert the gluing material into a liquid which is dispensed through a suitable discharge opening. To achieve this objective, the rod of gluing material is inserted into an elastic flexible cartridge and is fed therethrough either by mechanical apparatus or by manual pressure, in order to enter into the heating apparatus for liquifying the gluing material by heating.
The cartridge which receives the gluing material rod is preferably elastic and flexible, on the one hand, the gluing material rod has certain tolerances in thickness, and on the other hand, an easy insertion of the gluing material should be possible without the exertion of great care with regard to alignment of the rod when inserted into the cartridge. An elastic flexible cartridge facilitates insertion of the gluing material rod with the minimal amount of twisting and precisely and accurately guides the rod into the heater cavity.
Previous cartridges of this type, which are conventionally provided with a cylindrical-shaped channel opening have a number of disadvantages which can be traced back to various causes. For example, the cylindrical insertion channel which surrounds the gluing material rod applies a uniform surface friction over the entire surface of the engaging rod and cylindrical channel of the cartridge with the magnitude of the surface friction being directly related to the size of the surface area. Due to the surface friction, a relatively large force is required in order to advance the gluing material rod through the elastic cartridge into the heater. In addition, glue which has been liquified by the heater can flow back from the heater and enter into the space between the cartridge and the gluing material rod, in the event that the outer diameter of the rod is less than the inner diameter of the cartridge channel, thus leading to the possibility that the liquified glue can flow all the way to the insertion opening of the cartridge. Cooling of the liquified gluing material as it flows out of the heater and back into the cartridge will also cause an enlargement of the diameter of the portion of the gluing material rod which is yet to be advanced into the heater which leads again to an impairment of conventional gluing guns.